Ansible set_fact sets fact even when another fact is undefined?

[Ford FasteRR]

0down votefavorite

I'm seeing strange behavior in ansible 2.5.5 (on centos 6.10)

`facts_help.yml
---
- debug:
    var: fake_fact
- debug:
    var: new_fact

- set_fact:
    new_fact: fake_fact
    when: fake_fact is defined

- debug:
    var: fake_fact
- debug:
    var: new_fact`

I see this output:

PLAY [localhost] 
*********************************************************************

TASK [Gathering Facts] 
***************************************************************
ok: [localhost]

TASK [include_tasks] 
*****************************************************************
included: /etc/ansible/facts_help.yml for localhost

TASK [debug] 
*************************************************************************
ok: [localhost] => {
"fake_fact": "VARIABLE IS NOT DEFINED!"
}

TASK [debug] 
*************************************************************************
ok: [localhost] => {
    "new_fact": "VARIABLE IS NOT DEFINED!"
}

TASK [set_fact] 
**********************************************************************
ok: [localhost]

TASK [debug] 
*************************************************************************
ok: [localhost] => {
"fake_fact": "VARIABLE IS NOT DEFINED!"
}

TASK [debug] 
*************************************************************************
ok: [localhost] => {
    "new_fact": "fake_fact"
}

PLAY RECAP 
***************************************************************************
localhost                  : ok=7    changed=0    unreachable=0    failed=0

As you can see, fake_fact is undefined, and debug validates that. The when: clause evaluates to true, and allows new_fact to be set (that's my problem)..

Afterwards, a repeat of the debug on fake_fact still appears undefined.

So I'm not sure if this really a feature that I don't understand, a bug, or just a user error?

[Karl Auer]

The when clause should line up under set_fact. When I indent it properly, that play is skipped as expected. Not sure why the wrongly indented version is not picked up as a syntax error.

Here is the playbook I ran:

---
- hosts: localhost
  gather_facts: false
  become: false

  tasks:

     - debug:
         var: fake_fact
     - debug:
         var: new_fact

     - set_fact:
         new_fact: fake_fact
       when: fake_fact is defined
      
     - debug:
         var: fake_fact
     - debug:
         var: new_fact

And here are the results:

PLAY [localhost] ***************************************************************

TASK [debug] *******************************************************************
ok: [localhost] => {
    "fake_fact": "VARIABLE IS NOT DEFINED!: 'fake_fact' is undefined"
}

TASK [debug] *******************************************************************
ok: [localhost] => {
    "new_fact": "VARIABLE IS NOT DEFINED!: 'new_fact' is undefined"
}

TASK [set_fact] ****************************************************************
skipping: [localhost] => {"changed": false, "skip_reason": "Conditional result was False"}

TASK [debug] *******************************************************************
ok: [localhost] => {
    "fake_fact": "VARIABLE IS NOT DEFINED!: 'fake_fact' is undefined"
}

TASK [debug] *******************************************************************
ok: [localhost] => {
    "new_fact": "VARIABLE IS NOT DEFINED!: 'new_fact' is undefined"
}

PLAY RECAP *********************************************************************
localhost                  : ok=4    changed=0    unreachable=0    failed=0  

You are setting new_fact to the literal string "fake_fact", not to the value of a variable called fake_fact. Not sure that's relevant at this point.

Regards, K.

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--

Karl Auer

Email  : ka...@2pisoftware.com
Website: http://2pisoftware.com

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[Kai Stian Olstad]

On 21.08.2018 17:05, Ford FasteRR wrote:
> I'm seeing strange behavior in ansible 2.5.5 (on centos 6.10)
>
> `facts_help.yml
> ---
> - debug:
> var: fake_fact
> - debug:
> var: new_fact
>
> - set_fact:
> new_fact: fake_fact
> when: fake_fact is defined

Indentation error, when: is a property for the task.
Here you set a variable called when to the string "fake_fact is defined"

> As you can see, fake_fact is undefined, and debug validates that. The
> when:
> clause evaluates to true, and allows new_fact to be set (that's my
> problem)..
>
> Afterwards, a repeat of the debug on fake_fact still appears undefined.
>
> So I'm not sure if this really a feature that I don't understand, a
> bug, or
> just a user error?

User error.

--
Kai Stian Olstad

[Ford FasteRR]

Thanks for the update and clarification on this !!!